Warning issued for toxic algae discovery ---------------------------------------- People have been warned to beware after the discovery of potentially harmful algae in Yeadon Tarn. The presence of the blue-green algae species _Anabaena_ has been confirmed by the Environment Agency.

The tiny organisms are capable of producing toxic neurotoxins, which can harm anyone coming into contact with them.

The discovery has prompted the Parks and Countryside Department of Leeds City Council to put up notices around the Tarn warning the public of the danger and advising them to keep away from the water.

Groups using the Tarn have been told to ensure members know the procedures to follow to safe-guard their health.

People can become exposed to the neurotoxins by swallowing contaminated water, or by absorbing it through their skin. The toxins can also be swallowed by eating contaminated fish. A health alert was issued at the Tarn 2 years ago when traces of blue-green algae were found there.

[There are several blue-green algae species that can cause harm to people and animals. _Anabaena sp._ is one of those species. Anabaena forms bead-like chains, or barrel-like cells that appear to form chains. These nitrogen-fixing, blue-green algae are found both in solitary and colonial forms. Blue-green algae are often found in shallow water or water with high nutrient content, such as a large load of animal feces, or dead fish. They can form blooms across the water. Most blooms do not last too long, but they can last for several weeks in a few cases. Blue-green algaes are most likely to be prominent in warm weather, and in shallow water.

It is not uncommon to find that dogs that swim in these infested waters may be ill after swimming, and can die. It is not uncommon to find dead animals, sheep, cattle goats, horses, etc., dead within a few meters to a few hundred meters of the water source. People have become intoxicated and ill following ingestion of contaminated water.